3mbps after fibre install!?

I have recently switched to Talk Talk and had fibre installed by an engineer.

I was quoted i would receive 9-15mbps but as the title says i am receiving a steady 3mbps!

I have spokent to technical support and have been told the line is capable of 14mbps and there are no faults which although not great is better than 3mbps.

I have tried re-setting router, plugging in micro filter direct to test socket on master socket as instructed by technical support but no change.

Is there anything that can be done!?

Thanks.